The present invention relates to improvements in plastic film sheet structures for forming bags and the bags formed therefrom, particularly to a structure which permits the bag to be more readily opened.
More specifically, the invention relates to bags of the reopenable type which have shaped rib and groove profiles extending along the top that are openable by pulling apart top flanges above the profiles and are reclosable by pressing the rib and groove elements together. This type of bag is very useful for products which are removed from the bags only a portion at a time, or where the bags are to be reused. However, in many instances it is desirable to provide a bag which is sealed in the store and cannot be opened until eventually purchased. The advantages of this type of bag are obvious for foodstuffs and like materials wherein the potential customers must not be able to open the bag to remove a portion of the contents or contaminate the interior.
It is accordingly an object of the present invention to provide an improved sheet structure for forming a bag of the reclosable type wherein the bag has a structure which is completely sealed until used.
In the sealed reopenable type of bag, it is conventional to tear open the top of the bag above the reclosable rib and groove elements in such a manner as to provide flanges with which to separate the elements. This may be done by having the side walls of the bag either continuous or sealed at the top so that the top can be either cut or torn above the rib and groove elements along a line of weakened resistance or perforation before it is to be opened. The flanges which remain at the top of the bag after it is torn or cut enable the user to pull the rib and groove elements apart for access to the bag interior.
It is an object of the invention to provide a reclosable bag of the seated type with an improved tearing strip arrangement at the top which permits the bag to be made of very thin lightweight material or a laminated material. A feature of the present invention is to provide a bag structure wherein a tear line, where the film is too thin to be scored or perforated is required, or where because the film is of laminated construction and has sub-stantially greater strength, additional tearability or tear guidance is required, or wherein the functions of the interlocking rib and groove elements are not encumbered because of the thinness of the material, so that the provision of an easy to remove, yet strong tear strip at the top of the bag is permitted.
Various modifications, forms and arrangements of the invention are intended to be embodied and will become apparent to those skilled in the art from the teaching of the principles of the invention in connection with the disclosure of the claims, specification and drawings, in which: